convToMin3 13 == "221"
convToMin3 (-5) == "21"

incMin3 "122" == "110"
incMin3 "330" == "Ungueltige Eingabe"

haeufSort [2,3,1,2,1,1] == [1,1,1,2,2,3] 
haeufSort [1,3,2,3,1,3,2,2,1,1] == [1,1,1,1,3,3,3,2,2,2]

minMaxGrad [[1,0,1],[0,0,1],[1,1,0]] == (2,1)
minMaxGrad [[1,0,1,3],[0,1,1],[1,0]] == ((-1),(-1))